Seal for an electric machine located within a drive train of a motor vehicle

ABSTRACT

A relatively abrasion-free seal for an electric motor that is inserted within the motor vehicle drive mechanism ( 6 ) to an electric motor rotor located within the free construction space ( 4 ) of the wet-running electric machine rotor ( 2 ) or oil-cooled gearshift element of a multiple disk clutch ( 5 ) with which the very highest possible degree of an oil free annular gap ( 3 ) between the rotor ( 2 ) and the stator ( 1 ) of an electric machine is provided essentially in that the face side of the annular gap ( 3 ) is designed to have a seal ( 9 ) which, at a high rate of revolutions by the rotor ( 2 ) and depending on the type of gap seal, has been built to seal without touching.

This application is a national stage completion of PCT/EP2004/005330filed May 18, 2004 which claims priority from German Application SerialNo. 103 23 253.2 filed May 23, 2003.

FIELD OF THE INVENTION

The invention relates to a seal for an electric motor installed within amotor vehicle drive mechanism.

BACKGROUND OF THE INVENTION

Known already for some time now is a drive system for motor vehicleswhich, in addition to a conventional combustion engine, also has anelectric motor that is integrated into the drive mechanism of the motorvehicle either alternatively or also concurrently. These drive systems,known as “hybrid drives”, have many advantages from the ecological pointof view, since the mixed type of drive mechanism can also achievesignificant savings in energy in mixed driving (city/country) whencompared to an exclusively combustion engine drive.

Such hybrid drives for motor vehicles have been disclosed in DE 199 17665 A1, which has a first electric motor located within the drivemechanism between the combustion engine and the vehicle drive mechanismand a second electric motor permanently linked to a transmission driveshaft. Additionally, a gearshifting clutch is located between theelectric motor and the combustion engine operating as a motor and as agenerator.

In practice, the axial construction length of the motor vehicle drivemechanism, especially in the front traverse arrangement, plays asignificant role. In order to achieve an especially short drive design,it has been shown to be useful to take advantage of the freeconstruction space within the rotor of the electric machine. In thisrespect, it is know that at least one coupling of the drive system couldbe used there whereby, preferably a wet-running or, as the case may be,oil-cooled multiple disk clutch can be inserted.

Nevertheless it has shown to be disadvantageous when an annular gapbetween the rotor and the stator of an electric motor which, as suchshould remain free of oil, is used with the above noted cooling oil,since the centrifugal force created radially pushes the oil outwardthrough the disks of the multiple disk clutch and is returned in a largediameter back to the crankcase sump. In the studies completed with suchdiameters, and based on the usual number of revolutions, or because ofthe high rate of rotation of the motor vehicle's drive mechanism or, asthe case may be, its peripheral velocity affecting the seals, these havenot been shown to be useful for the annular gap, since they aresubjected to a relatively high rate of wear and tear. Here is where theinvention described in the following text enters the picture.

The purpose of the invention is to provide a relatively abrasion-freeseal for an electric motor that is inserted within the motor vehicledrive mechanism to an electric motor rotor located within the freeconstruction space of the wet-running electric machine rotor, or as thecase may be, oil cooled gearshift element, for example, of a multipledisk clutch, with which an annular gap, free of oil to the highestdegree possible, between the rotor and the stator of an electric machineis practicable.

According to the invention, this task together is solved in that inorder to achieve the highest possible level oil-free annular gap betweenthe rotor and the stator of the electric motor, at least one lining isto be arranged at the front-facing side of the annular gap, which forits part, is designed to seal, at least at high rate of rotation by therotor, without touching.

According to an advantageous design of the invention, the lining isfashioned in such way and arranged on the rotor so that at a standstillor at a low rate of rotation it seals the annular gap by being incontact and that at a high rate of rotation, it is released from theannular gap.

Furthermore, it is recommended, in the sense of the invention, that thelining be formed through a more or less familiar V-ring.

Additionally, it is foreseen that the annular gap, preferably at thelocation of the lining that is on the opposite side of the electricmachine, be linked to an air intake opening.

Finally, it is recommended that the air intake opening be connectedthrough a vent pipe with the interior of the motor vehicle drivemechanism that is linked to the vehicle transmission.

SUMMARY OF THE INVENTION

According to the invention, the seal of the electric motor that isattached within a motor vehicle drive mechanism to a radial of the wetrunning gearshift element placed within the free construction space ofthe electric motor rotor gear as, for example, a multiple disk clutch ora multi-disk brake which provides, first of all, in view of the state ofthe art of technology, for a significant advantage in that thepenetrating oil will already be carried away from it into the annulargap. Furthermore, this seal is simple to engineer and is judged to causeespecially little abrasion. By using the measures according to theinvention, the electric motor will remain functional for a longer periodof time so that it can remain at a standstill for longer periods oftime. In addition, the working life of the oil is increased, since in ahot annual gap, the oil will be damaged.

Moreover, because of the low rate of abrasion, the use of a V-ring wouldhave hardly any negative affect on the electric motor torque. Thespecial construction of the V-ring has the effect that with a minimum ofloss in performance it falls back even more with the increasing rate ofrotation. Also, such a V-ring at a standstill can effectively preventpenetration of oil into the annular gap.

BRIEF DESCRIPTION OF THE DRAWING

The invention will now be described, by way of example, with referenceto the accompanying drawing in which:

The sole FIGURE shows a schematic of a partial lengthwise section of anelectric motor arranged within a motor vehicle drive mechanism.

DETAILED DESCRIPTION OF THE INVENTION

There follows the well-known electric motor arrangement, which can beused as either a drive motor or as a generator, and which consists of astator 1 and a turning rotor 2 placed in it with an annular gap 3pictured between them.

Arranged within a free construction space 4 of the rotor 2 is a gearclutch in the form of a wet-running or, as the case may be, anoil-cooled multiple clutch disk 5, which is connected to afunction-linked motor vehicle drive mechanism 6. In place of a multipledisk clutch, a multiple disk brake can also be used.

During the operation of the multiple disk clutch 5, oil will be neededto cool it which, as explained above, flows from a crankcase sump (notrepresented here), and is taken up by disks 7 of the multiple diskclutch 5 and, because of the centrifugal force, flows out again in thesame radial path. Subsequently, the cooling fluid flows through acooling oil drain 8 in a large diameter back into the crankcase sump.

During the earlier explained oil cooling, unintentional oil penetrationcan occur into the annular gap 3, which may be damaging to the functionand the life span of the electric motor.

In order to counter this problem, that is to say, to largely prevent oilpenetration into the annual gap 3 during the operation of the electricmotor or to push it out as fast as possible, the invention provides atthe front-facing side of the annular gap 3 for at least one lining 9which, for its part, at least at a high rate of revolution by the rotor2, depending on the type of the gap seal, has been designed to sealwithout touching.

In terms of its function, the gap seal is such that, as soon as theelectric machine or, as the case may be, its rotor 2 is turning, the oillocated in the annular gap 3 moves out of the annular gap 3 as a resultof the effect of centrifugal forces. Further, the turning of the rotor 2generates an air stream which also prevents the penetration of oil fromthe outside into the annular seal 3.

In order to advantageously support the removal of oil from the annulargap 3, according to a preferred design of this invention, an air intakeopening 10 is indicated, which can be included at the front-facing sideof the electric machine located opposite the lining 9, from where afurther reinforced air flow within the annular gap 3 drives out the oil,and also in the area of the lining 9 (the gap lining) prevents thepenetration of the oil from the outside into the annular gap 3 as soonas low rates of rotation of the rotor 2 occur.

It has been proved to be advantageous to link the air intake opening 10through a vent pipe with the drive interior of a motor vehicle drivemechanism-connected vehicle transmission.

Additionally, under certain circumstances, oil penetration into theannular gap 3 can also occur in the case of an electric motor being at astandstill or, as the case may be, at the stopped multiple disk clutch 5and the corresponding skewed transmission position.

In order to counter such a nuisance, the lining 9 is advantageouslydesigned and placed on the rotor 2 so that it will seal the annular gap3 even at a standstill or at a low rate of rotation while touching, andat a high rate of rotation will release the annular gap 3 so that amaximally effective the gap seal can be developed.

The already-known V-ring has proven itself as especially suitable forthe design of a lining 9 such as that described, and its advantages havebeen described in greater detail above.

REFERENCE NUMERALS

-   1 stator-   2 rotor-   3 annular gap-   4 construction space-   5 multiple disk clutch-   6 motor vehicle drive mechanism-   7 disks-   8 cooling oil drainage-   9 lining-   10 air intake opening

1-5. (canceled)
 6. A seal of an electric motor that is installed withina motor vehicle drive mechanism within a free construction space of oneof a wet-running electric motor rotor, oil-cooled disk gearshiftelement, a multiple disk clutch and a multiple disk brake, the sealcomprising: to achieve a very high degree of oil-free annular gap (3)between the rotor (2) and a stator (1) of the electric motor at a faceside of an electric machine annular gap (3), at least one lining (9) isarranged so that, at least at a high rate of rotation of the rotor (2),depending on a type of a gap lining, the seal is designed to sealwithout touching.
 7. The seal according to claim 6, wherein the lining(9) is designed in such way and arranged on the rotor (2), that duringone of a standstill or at a low rate of rotation speed, the lining sealsthe annular gap (3) by touching and releases the annular gap (3) at ahigh rate of rotation speed.
 8. The seal according to either claim 6,wherein the lining (9) is built through a known V-ring.
 9. The sealaccording to claims 6, wherein in the annular gap (3), preferably at thelining (9), an air intake opening (10) is designed opposite the faceside of the electric motor.
 10. The seal according to claim 9, whereinthe air intake opening (10) is connected through an air vent to aninterior of a transmission of a motor vehicle gear mechanism connectedvehicle drive.
 11. A seal of an electric motor installed within a motorvehicle drive mechanism within a free construction space of one of awet-running electric motor rotor, a multiple disk clutch and a multipledisk brake, the seal comprising: at least one lining (9), arranged suchthat at a high rotational rate of a rotor, depending on a type of gaplining, the lining (9) seals without touching, to achieve a very highdegree of oil free annular gap (3) between the rotor (2) and a stator(1) of the electric motor at a face side of the annular gap (3)